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Subject: Re: A bunch more automatically generated mates in 3...

Author: Colin Frayn

Date: 03:59:10 06/21/02

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On June 21, 2002 at 04:33:23, Georg v. Zimmermann wrote:

>this thing is very cool! I read you already tried restrictions like "first move
>doesnt check, no capture moves" etc. How do the resulting mates look like ?

I guess they're just slightly less obvious.  The next trick is to add in "Force
legal first ply moves for black king", i.e. pretend that the board is set up for
black, not white, and make sure that the black king actually has legal moves.

The problem is that most positions now just involve a heavily blockaded black
king, and just require piling pieces into the battle until CM is attained, but
the route is normally obvious.  Not very many of them are actually particularly
clever.  Also, the code isn't very well optimised yet so it probably isn't
anywhere near as fast as it could be.  When generating crowded mate in 3
problems it tends to take ages.

>How about something like "white to mate in 3, white only has knight, black at
>least materialValue > 800, no checking moves" (Is that even possible, I am
>curious).

You set up the pieces on each side, so something like this is possible, but
you'd have to set up black's pieces individually.  It might take ages ;)

>How does the mate generation work ? Completely trial and error ?

Pretty much.  I really can't see any particularly clever way of generating mate
problems by another method.  Maybe I could try to constrain the board positions
a bit, but it's probably not going to help much.  I'm thinking of generating
only sensible pawn formations and forcing bishops on opposite coloured squares
(ATM it's possible for, say, white to have two white-square bishops.  I guess
that *could* happen in a game but it's unlikely).

Download from here;
http://www.ast.cam.ac.uk/~cmf/chess/index.html

about 2/3 of the way down under "Download my Checkmate Test Generation Program".

Cheers,
Col



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